Forecasts from the National Weather Service and major models indicate an overnight low in the mid-70s for Dallas on September 21, driven by high humidity, light northeast winds, and partial cloud cover that limits radiative cooling after daytime highs near 92–94°F. Recent warm, moist air advection from the southeast, combined with a 20–50% chance of afternoon or overnight thunderstorms, has kept surface temperatures elevated compared to drier historical analogs. This aligns with the market’s tight clustering around 74–79°F outcomes, where 76–77°F leads at 29% implied probability as traders weigh consistent model guidance against minor uncertainties in storm timing and wind shifts that could allow slightly more cooling. Updated NWS briefings and evening model runs will provide the next key data points before resolution.